The subject matter disclosed herein generally relates to electromechanical systems. More specifically, the subject disclosure relates to torque sensing in electromechanical systems.
With recent advances in electric motor and electric motor drive technology, it has become advantageous to replace the traditional mechanical, pneumatic and hydraulic systems on vehicles such as aircraft, spacecraft, ships and land vehicles with electrically driven systems. Electrically driven systems offer the advantages of greater efficiency, reduced weight, higher reliability, reduced environmental and fire hazard from hydraulic fluid, reduced maintenance cost and smaller packaging. In load carrying applications such as electromechanical actuators, starter-generators, electrically driven pumps, rotational torque in excess of safe design margins, or overload torque, can occasionally be applied to the system. Safety during an overload condition is of the utmost importance.
The need to sense the mechanical overload condition requires that the load be sensed and acted upon in an appropriate time frame to prevent mechanical or electrical damage to the system and the external surroundings. Typically, mechanical or electrical load/force sensors are used to protect drive systems. Adding sensors to an actuation system, however, reduces its reliability and increases the overall system complexity. Mechanical actuation systems require accurate mechanisms that allow relief of the mechanical loads that exceed a design threshold. Mechanical safety features such as shear shafts, brakes, slip clutches and load sensors have traditionally provided overload protection but have limitations. Similarly, hydraulic and pneumatic actuation systems typically utilize a spring loaded pressure relief valve that opens when the system pressure/system load exceeds the design threshold. The art would well receive an overload protection apparatus that provides accurate system protection without increasing complexity of the system or reducing the overall system reliability.